Mobile request handling for Ruby on Rails
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Note: At next version (1.6) only ruby >= 1.9 will be supported.


This gem works by adding the 'mobile' format to your rails application. Whenever a request come from a mobile device, if you have your controller mobile enabled, it shall render the instead of the view.html.erb (or haml, or whatever).

How does it work?

By adding “respond_to_mobile_requests” in your application_controller (or any other controller), your controllers (or that controller) will understand mobile requests as a new mime type alias “mobile”. This will make the controller to search for the .mobile.erb file instead of the .html.erb. Also you will be able to do:

respond_to do |format|
  format.html   { ... } { ... }


Add the gem to your gemfile:

gem 'mobylette'

And add to your ApplicationController.rb (for enabling it to all your controllers) or to the controllers you want this functionality on:


After that, you may start adding your .mobile. views.


  • is_mobile_request?

    This helper returns true if the request comes from a mobile device, false if it does not.

  • is_mobile_view?

    Returns if the current format is :mobile or not.

There is a difference between is_mobile_view? and is_mobile_request?. You may have a user requesting from a mobile device (is_mobile_request? == true) and at the same time, you may use the sesssion override to render de default format aways (is_mobile_view? == false). There are a lot of other combinations where these 2 functions will return different results.

* is_mobile_request?  -> Exclusively checks for the device from where the request were made
* is_mobile_view?     -> Exclusively checks for the view format been rendered
  • mobylette_stylesheet_link_tag(*sources)

    This works like the stylesheet_link_tag helper, but when the request comes from a mobile device, it adds “_mobile” to the stylesheets before calling stylesheet_link_tag

  • mobylette_javascript_include_tag(*soruces)

    Same as mobylette_stylesheet_link_tag, but for javascript files and javascript_include_tag

Fall Backs

By default, when the mobile format is not found, mobylette will fall back to the request original format. For example, if a cell phone makes a request by html, and there is no mobile view, it will render the html. You may force it always to fall back to a especific format, by passing the :fall_back parameter to the respond_to_mobile_requests method:

respond_to_mobile_requests :fall_back => :html

This would force all views (mobile) to fall back to the html views. You may also disable this behavior, and no fall back will ever occur:

respond_to_mobile_requests :fall_back => false

XHR Requests

By default the mobile device verification will skip XHR requests, and these will be served as if mobylette wasn't there. You can override this behavior by passing the :skip_xhr_requests => false to the respond_to_mobile_requests call.

respond_to_mobile_requests :skip_xhr_requests => false

You may need to use this if you are using JQuery mobile or something similar in your application.

Skiping mobile filter

In the case you need to skip a mobile_request for been treated as mobile, you can pass the `skip_mobile=true` param to the url/request.

For example, you are using jquery_mobile and by that `:skip_xhr_requests => false`, but there is a special case where you need to process an Ajax, then you can use this param.

Forcing/Ignoring Mobile Requests

You may force your user to aways render the mobile format, or to aways render the default request format (when the request comes from a mobile device). You can use the session var :mobylette_override for doing it:

session[:mobylette_override] = :ignore_mobile

This will skip the code that would force the mobile format. By doing this, your user will aways render the 'original' version of your app.

session[:mobylette_override] = :force_mobile

This will force the mobile format rendering, no matter from where the user is requesting it (unless it's a xhr request).

session[:mobylette_override] = nil

This will disable any override (default).


Don't drive your mobylette without your Helmet! It's safer to do tests!

For testing, include the Mobylette::Helmet module to your test/test_helpers.rb:

require 'mobylette/helmet'
include Mobylette::Helmet

For RSpec: add to your spec/spec_helpers.rb or create a spec/support/mobylette.rb with the following:

require 'mobylette/helmet' 
RSpec.configure do |config|
  config.include Mobylette::Helmet, :type => :controller

This will add 2 methods to your test scope:


this one will force a mobile user_agent, allowing you to test mobile requests.


and this one will reset your user_agent to the test default “Rails Testing”. You don't need to call this everytime, all your requests by default are “Rails Testing” in your test env.

Friendly note: on your tests, call these functions BEFORE you make the request, otherwise they are useless =p

Contributions and Credits

This gem is based on the mobile_fu plugin (

Also, these pages were very usefull when creating the gem: